A state-of-the art Philips CM100 transmission electron microscope is requested for shared use by investigators in the Zoology, Genetics, Biochemistry, and Botany Departments. This microscope will provide high contrast and high resolution transmission electron microscopy of specimens, can rapidly product large numbers of focused images, is chromatically corrected to image thick sections without edge-blurring, and is equipped with a eucentric goniometer for stereo images. The microscope will be integrated into the Department of Zoology's computer system via a CCD TV camera to directly transfer images onto computer disk storage and archiving for image analysis and 3-D reconstruction. This instrument will be housed in the Zoology Department, replacing a 20 year- old Philips 300. The EM laboratory has excellent space for sample preparation, including fixation, embedding, sectioning and vacuum evaporating. Day-to-day operations will be overseen by a highly experienced technician who will also assist in sample preparation. The CM100 will be used primarily by 3 labs to pursue ongoing NIH-funded research programs with significant focuses on ultrastructural analysis of cells and cellular interactions. These investigators have years of cumulative electron microscopy experience and various areas of specialized technical expertise. Interactions among the group will foster scientific and technical progress on current and future research projects in areas ranging from membrane structure to neural function. Approximately 1/2 of the microscope usage will be shared by 16 additional laboratories (8 with NIH funding) whose research requires electron microscopy for less extensive projects. The microscope will also be accessible to other investigators for pilot or short-term projects, extending the usefulness of the instrument to the broadest possible constituency. In addition, availability of a reliable, easily accessible, high-resolution transmission electron microscope will contribute to graduate student training, directly benefitting the Interdisciplinary Molecular and Cellular Biology, Developmental Biology and Genetics training grant programs.